High-resolution electric field sensor in cover glass

ABSTRACT

A fingerprint sensor is described that includes a thin protective cover layer on a sensor glass layer with receive circuitry between the thin protective cover layer and the sensor glass layer. In an implementation, a fingerprint sensor assembly includes a controller; a metal layer configured to be electrically coupled to the controller; a transmit layer electrically connected to the metal layer and the controller; a sensor glass layer including at least one through-glass via, where the transmit layer is disposed on a first side of the sensor glass layer, and where the transmit layer is electrically coupled to the at least one through-glass via; a receive layer disposed on a second side of the sensor glass layer, where the receive layer is electrically coupled to the at least one through-glass via; and a protective cover layer disposed on the receive layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. §119(e) ofU.S. Provisional Application Ser. No. 62/028,887, filed Jul. 25, 2014,and titled “PHOTOPATTERNABLE GLASS MICRO ELECTROCHEMICAL CELL ANDMETHOD.” U.S. Provisional Application Ser. No. 62/028,887 is hereinincorporated by reference in its entirety.

Electronic devices utilizing a touchscreen are prevalent in today'stechnology. Electronic devices using a touchscreen can include, forexample, a smartphone, a smartwatch, or a tablet computer. A touchscreencan include an electronic visual display that a user can control throughsimple or multi-touch gestures by touching the screen, for example witha finger. The user can use the touchscreen to react to what is displayedand to control how it is displayed (for example by zooming the textsize). The touchscreen enables the user to interact directly with whatis displayed, rather than using a mouse, touchpad, or any otherintermediate device (other than a stylus, which is optional for mostmodern touchscreens).

Fingerprint sensors can include a device used to capture an image of afingerprint pattern. These fingerprint patterns can be used to create arepresentative template, which can be stored and used for matching anindividual's fingerprint.

SUMMARY

A high-resolution electric-field sensor fabricated on a cover glass isdescribed. The cover glass is placed above a display to protect thedisplay device from scratches, breakage, and other damage. Thehigh-resolution electric-field sensor can resolve the fine features of afingerprint on the cover glass while still imaging fingers, styli,palms, and human body parts both on the cover glass and above the coverglass. The cover glass retains its strength, scratch resistance, andtransparency even in the presence of the high-resolution electric-fieldsensor. The result is that sensing of many different objects can be doneabove the display.

Accordingly, a fingerprint sensor is described that includes a thinprotective cover layer on a sensor glass layer with receive circuitrybetween the thin protective cover layer and the sensor glass layer. Inan implementation, a fingerprint sensor assembly includes a controller;a metal layer configured to be electrically coupled to the controller; atransmit layer electrically connected to the metal layer and thecontroller; a sensor glass layer including at least one through-glassvia, where the transmit layer is disposed on a first side of the sensorglass layer, and where the transmit layer is electrically coupled to theat least one through-glass via; a receive layer disposed on a secondside of the sensor glass layer, where the receive layer is electricallycoupled to the at least one through-glass via; and a protective coverlayer disposed on the receive layer.

In an implementation, a cover glass assembly with a high-resolutionelectric field sensor that employs example techniques in accordance withthe present disclosure includes a transmit layer electrically connectedby a metal layer to a controller; a sensor glass layer including atleast one through-glass via, where the transmit layer is disposed on afirst side of the sensor glass layer and is electrically coupled to theat least one through-glass via; a receive layer disposed on a secondside of the sensor glass layer, where the receive layer is electricallycoupled to the at least one through-glass via; and a protective coverlayer disposed on the receive layer, where the cover glass device isconfigured to include a touch-panel device.

In an implementation, a cover glass assembly with a high-resolutionelectric field sensor that employs example techniques in accordance withthe present disclosure includes a display assembly configured for amobile device; a transmit layer electrically connected by a metal layerto a controller, where the controller is electrically coupled to thedisplay assembly; a sensor glass layer including at least onethrough-glass via, where the transmit layer is disposed on a first sideof the sensor glass layer and is electrically coupled to the at leastone through-glass via; a receive layer disposed on a second side of thesensor glass layer, where the receive layer is electrically coupled tothe at least one through-glass via; and a protective cover layerdisposed on the receive layer.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

DRAWINGS

The detailed description is described with reference to the accompanyingfigures. The use of the same reference numbers in different instances inthe description and the figures may indicate similar or identical items.

FIG. 1 is a partial cross section side view illustrating an embodimentof a touch panel device that includes a thick protective cover layer andsensor glass.

FIG. 2 is a partial cross section side view illustrating an embodimentof a touch-panel device and/or cover glass device that includes a thinprotective cover layer and sensor glass with through-glass vias, inaccordance with an example implementation of the present disclosure.

FIG. 3 is a front view illustrating an embodiment of a touch-paneldevice and/or a cover glass device that includes a fingerprint sensor inthe bottom center portion of the cover glass device, in accordance withan example implementation of the present disclosure.

FIG. 4 is a front view illustrating an embodiment of a touch-paneldevice and/or a cover glass device that includes a fingerprint sensor inthe bottom right portion of the cover glass device, in accordance withan example implementation of the present disclosure.

FIG. 5 is a front view illustrating an embodiment of a touch-paneldevice and/or a cover glass device that includes a fingerprint sensor inthe entire portion of the cover glass device, in accordance with anexample implementation of the present disclosure.

FIG. 6 is a diagram illustrating an embodiment of a fingerprint sensorthat includes a sensor glass layer with through-glass vias and a thinprotective cover layer, in accordance with an example implementation ofthe present disclosure

DETAILED DESCRIPTION Overview

Some existing smartphones and computing devices have added fingerprintsensors in the home buttons or on the back side. Generally the designtrend is for the display area to increase to the edges of the front faceand potentially wrap around the sides. In the future, the physical homebutton may no longer exist, and the fingerprint sensor may need to beover the display area and may need to co-exist with a touch sensor, astylus sensor, a hover sensor, and/or a gesture sensor.

A fingerprint sensor may have low sensitivity due to thick cover glass(e.g., sometimes 0.5-0.7 mm). In particular, the sensitivity of thesefingerprint sensors with thick protective cover glass may be too low foraccurate fingerprint detection above the display with indium tin oxidelayers traditionally placed under the protective cover glass.

A fingerprint sensor is described capable of imaging fingerprints sensedby the fingerprint sensor and cover glass device, capacitive imaging ofmotion of multiple fingers in contact with the fingerprint sensor andcover glass device, capacitive imaging of approximate positions offingers (“hovering”) above the fingerprint sensor and cover glassdevice, and motions (“gestures”) of hands in proximity to thefingerprint sensor and cover glass device. The fingerprint sensor andtouch panel device disclosed herein provide improved sensitivity byplacing a receive layer between the sensor glass layer and theprotective cover layer and bringing the leads from the receive layer toa transmit layer on the opposite side of the sense glass by way ofthrough-glass vias in the sensor glass layer. Additionally, thefingerprint sensor and cover glass device provide a thinner fingerprintsensor and faster fingerprint detection because of the thin protectivecover layer and the through-glass via configuration.

A capacitive touch sensor typically is constructed to provide mutualcapacitance between transmit rows (parallel to “x”) and receive columns(parallel to “y”). The transmit rows and receive columns can be at thesame distance from the top surface (e.g., protective cover layer 136) ofthe sensor, or the receive columns can be closer to the top surface. Inimplementations, typical thicknesses of a protective cover glass can be0.4 to 0.7 mm. A controller integrated circuit provides signals(typically in the 50-KHz to 10-MHz frequency range) to the transmit rowsand detects changes in mutual capacitance to the receive columns fromthe amplitude and phase of the received signals. These changes in mutualcapacitance represent the presence of a finger, stylus, and/or object inthe vicinity of the pixels defined by the intersection of a transmit rowand receive column. In implementations, the spatial period (“pitch”) ofa touch sensor can typically be about 5 mm.

The tip of a stylus is often smaller than a fingertip, typically 1 to 2mm in diameter. Thus, a touch sensor can often be optimized for finerspatial resolution in order to better localize the position of thestylus. The touch sensor pitch may be about 5 mm, but it uses knowledgeof the spatial sensitivity of a single pixel and neighboring pixels tobetter locate the stylus. Cover glass thicknesses can be 0.4 mm to 0.7mm, which is similar to the thickness of a capacitive touch sensor.

A fingerprint sensor must be able to detect and image the ridges andvalleys of a fingerprint. These fingerprint features have a pitch of afew hundred microns (e.g., 400 μm), and the valleys are a few hundredmicrons below the ridges. A finer fingerprint sensor pitch is needed toform an accurate image of these fingerprint features. The industrystandard (and required for certain government applications) is a pitchof 50 microns, nearly 100 times less than the 5-mm pitch of typicaltouch sensors. Capacitive sensing of the fine ridges and valleys of afingerprint requires a cover glass that is considerably thinner than the0.4 to 0.7 mm that is standard for touch sensors.

A hover sensor must detect the presence of a finger that is a few toseveral centimeters above the hover sensor. It needs to give theapproximate position of the finger in x and y coordinates. Often, thehover sensor can include a touch panel operated in a different,low-spatial-resolution mode. This might be achieved, for example, byganging together multiple transmit and receive elements. A gesturesensor can include an extension of a hover sensor for detecting andclassifying motions of a hand on or above a touch panel.

However, some touch panels cannot resolve the fine features of afingerprint, simply because, with a typical pitch of 5 mm, they grosslyspatially undersample fingerprint ridges that have a pitch around 400um.

Existing capacitive fingerprint sensors can include silicon integratedcircuits. Silicon integrated circuits are opaque and cannot be placedover a display, which is where a fingerprint sensor needs to be in orderto function. Other fingerprint sensors that use optical techniques needa large distance between the fingerprint and the camera and thus aretotally unsuitable for mobile devices.

The fingerprint sensor disclosed herein solves the sensing of afingerprint by using a transmit and receive pitch of about 50 to 100microns, moving the transmit layer and especially the receive layercloser to the actual finger, and using a hard and virtually scratchproofmaterial for the protective cover glass. The receive layer should beless than 100 microns away from the finger for obtaining the bestfingerprint image.

Accordingly, a fingerprint sensor is described that includes a thinprotective cover layer on a sensor glass layer with receive circuitrybetween the thin protective cover layer and the sensor glass layer. Inan implementation, a fingerprint sensor assembly includes a controller;a metal layer configured to be electrically coupled to the controller; atransmit layer electrically connected to the metal layer and thecontroller; a sensor glass layer including at least one through-glassvia, where the transmit layer is disposed on a first side of the sensorglass layer, and where the transmit layer is electrically coupled to theat least one through-glass via; a receive layer disposed on a secondside of the sensor glass layer, where the receive layer is electricallycoupled to the at least one through-glass via; and a protective coverlayer disposed on the receive layer. In implementations, a cover glassassembly with a high-resolution electric field sensor that employsexample techniques in accordance with the present disclosure includes atransmit layer electrically connected by a metal layer to a controller;a sensor glass layer including at least one through-glass via, where thetransmit layer is disposed on a first side of the sensor glass layer andis electrically coupled to the at least one through-glass via; a receivelayer disposed on a second side of the sensor glass layer, where thereceive layer is electrically coupled to the at least one through-glassvia; and a protective cover layer disposed on the receive layer, wherethe cover glass device is configured to include a touch-panel device. Inimplementations, a cover glass assembly with a high-resolution electricfield sensor that employs example techniques in accordance with thepresent disclosure includes a display assembly configured for a mobiledevice; a transmit layer electrically connected by a metal layer to acontroller, where the controller is electrically coupled to the displayassembly; a sensor glass layer including at least one through-glass via,where the transmit layer is disposed on a first side of the sensor glasslayer and is electrically coupled to the at least one through-glass via;a receive layer disposed on a second side of the sensor glass layer,where the receive layer is electrically coupled to the at least onethrough-glass via; and a protective cover layer disposed on the receivelayer.

Example Implementations

FIGS. 1 and 2 illustrate a cross section view of a fingerprint sensor100. A fingerprint sensor 100 can include a fingerprint sensor assembly,a cover glass assembly, and/or a fingerprint sensing mobile device. Asillustrated in FIGS. 1 and 2, the fingerprint sensor 100 can include atransmit layer 104, a sensor glass layer 108, a receive layer 112, and aprotective cover layer 116. The transmit layer 104 (e.g., disposed on afirst side of the sensor glass) can function to drive a strong electricfield into the region above the receive layer 112. In one specificembodiment, the transmit layer 104 can include a layer of indium tinoxide (ITO) rows. Indium tin oxide can serve as a good signal routinglayer due to its electrical conductivity and optical transparency.Additionally, in embodiments, indium tin oxide can be formed as a thinfilm. The indium tin oxide layer can be deposited using techniques suchas physical vapor deposition, electron beam evaporation, and/orsputtering. In some additional embodiments, the transmit layer 104 caninclude metal mesh, silver nanowires, and/or carbon nanotubes.

In implementations, the transmit layer 104 can be electrically coupledto a metal layer 106, which can be formed using techniques, such aslithography, deposition, and etching on a small scale, or othertechniques such as placing wiring for a larger scale. The metal layer106 can function to connect the supplies, inputs, and outputs of thecontroller 130 to the receive layer 112, transmit layer 104, or aflexible flat cable and/or a flexible printed circuit board. Theflexible printed circuit board and/or metal layer 106 can connect thecontroller 130 to a printed circuit board 138, for example. Asrepresented in FIG. 2, 138 can include a flexible printed circuit boardand/or a printed circuit board. Additionally, the controller 130 candetect the changes in mutual capacitance between the lines on thereceive layer 112 and the lines on the transmit layer 104. Inembodiments, the metal layer 106 can include any suitable conductivematerial, such as wires of copper, aluminum, etc.

The fingerprint sensor 100 can include a sensor glass layer 108, asillustrated in FIGS. 1 and 2. In implementations, the sensor glass layer108 can include a thin glass substrate configured to let light pass froma display assembly 102 through the fingerprint sensor 100 to a userwhile providing mechanical support. In some embodiments, a sensor glasslayer 108 thickness of about 400 microns can provide both strength andan adequate spatial modulation transfer function for the transmit layer104. It is contemplated that the sensor glass layer 108 can be ofvarying thickness (e.g., 300 microns, 500 microns, etc.). In onespecific embodiment, the sensor glass layer 108 includes a thin glasssubstrate, such as an alkali-aluminosilicate sheet toughened glassmanufactured through immersion in a molten alkaline salt bath using ionexchange to produce compressive residual stress at the surface. Inanother embodiment, the sensor glass layer 108 can includesoda-lime-silica glass. It is contemplated that other types of glass mayalso be utilized. The sensor glass layer 108 can be chosen and/orconfigured for breakage resistance. If additional strength is desired,the fingerprint sensor 100 can, in some embodiments, include at leastone additional sensor glass layer 108. In a specific embodiment, asecond sensor glass layer 108 can be laminated between the transmitlayer 104 and the metal layer 106 for additional strength. In onespecific embodiment, the transmit layer 104 can include a wiring patternthat includes a controller 130 in a chip-on-glass configuration and/or aribbon cable configured to receive from and/or transmit signals to amotherboard or other device.

The sensor glass layer 108 can include at least one through-glass via110. In implementations, a through-glass via 110 can include a throughsubstrate via in the sensor glass layer 108. The through-glass via 110can be backfilled with a conductive material, for example copper, orcoated with a conductive material. The copper and/or conductive materialcan be electrically coupled to the transmit layer 104 and/or a receivelayer 112. In one specific example, the at least one through-glass via110 can include a metal-filled blind via that extends from the firstside of the sensor glass layer 108 to the second side of the sensorglass layer 108, where the metal-filled blind via is configured toprovide capacitive coupling between the transmit layer 104 and thereceive layer 112. A blind via can include a via that is exposed on onlyone side of the sensor glass layer 108. In one example, thethrough-glass via 110 can be laser-drilled. In some implementations, thefingerprint sensor 100 can include multiple through-glass vias 110disposed in a bezel area (e.g., the outer area and/or area proximate tothe edge of the fingerprint sensor 100) that bring receive signals fromthe receive layer 112 to the transmit layer 104. Utilizing athrough-glass via 110 can function to take leads from a transmit layer104 on a first side of the sensor glass layer 108 to a receive layer 112on a second side of the sensor glass layer 108 and eliminate flex cablesand obviate awkward wiring on the receive layer 112 side (e.g., side ofthe sense glass 108 distal from the transmit layer 104) of the sensorglass layer 108. Bringing the receive signals from the receive layer 112to the transmit layer 104 through the through-glass via(s) 110 providesa neater, thinner, and more compact assembly.

The fingerprint sensor 100 can include a receive layer 112 disposed onthe sensor glass layer 108. The receive layer 112 functions to sense thechange in capacitance due to a fingerprint, touch, stylus, hoveringfinger, or gesturing hand. In implementations, the receive layer 112 caninclude a transparent conductor, such as indium tin oxide (ITO), whichcan be patterned on the surface of the sensor glass layer 108. Thereceive layer 112 can be deposited using techniques such as physicalvapor deposition, electron beam evaporation, and/or chemical vapordeposition. The receive layer 112 can be configured to route signalsand/or provide electrical communication to and/or from the transmitlayer 104 by way of at least one through-glass via 110.

The fingerprint sensor 100 can include a protective cover layer 116disposed on the receive layer 112 and sense glass layer 108. Theprotective cover layer 116 can include a protective layer and/or coverlayer for the fingerprint sensor 100 and can be scratch-resistant aswell as provide insulation for the receive layer 112. In one specificembodiment, the protective cover layer 116 can include a thin singlecrystal layer, such as sapphire, which may be laminated on the receivelayer 112 and the sensor glass layer 108. Sapphire is a hard naturalmaterial and can be difficult to scratch. Sapphire can function well asa protective cover layer 116. In one specific embodiment where theprotective cover layer 116 includes sapphire, the single crystalsapphire layer can be approximately 100 μm to approximately 200 μm inthickness. In another specific embodiment, the protective cover layer116 can include a hard thin film. In this specific embodiment, theprotective cover layer 116 can include, for example, silicon nitride,aluminum oxide, silicon carbide, and/or diamond. In one specificembodiment, a protective cover layer 116 includes a layer of aluminumoxide with a thickness of about one μm. In implementations, a protectivecover layer 116 including a hard thin film can be a conformal coating infull contact with the sensor glass layer 108 and/or the receive layer112 (e.g., the indium tin oxide layer).

The protective cover layer 116 may serve as a protective coating and/oran anti-reflective coating for the fingerprint sensor 100. Theprotective cover layer 116 functions as a touch surface upon which auser can use one or more fingers, a stylus, and so forth to inputcommands to the touch screen device 100. In some implementations, theprotective cover layer 116 is an at least substantially transparentdielectric. Utilizing a thin protective cover layer 116 can allow thereceive layer 112 to be disposed within several hundred microns, tens ofmicrons, or even a few microns of a user's finger or stylus. The highdielectric constants of sapphire and/or the thin film further enhancesensitivity.

As shown in FIG. 1, the fingerprint sensor 100 may include a displayassembly 102 (e.g., a liquid crystal display (LCD) and/or an organiclight-emitting diode (OLED)). In an implementation using an LCD, adisplay assembly 102 can include a display that employs the lightmodulating properties of liquid crystals. LCD displays can utilize twosheets of polarizing material with a liquid crystal solution betweenthem. An electric current passed through the liquid causes the crystalsto align so that light cannot pass through them. Each crystal functionsas a shutter either allowing light to pass through or blocking thelight. Some embodiments of a display assembly 102 can include a videodisplay, a flat panel display, an electronic visual display, a computermonitor, and/or an active-matrix organic light-emitting diode. Inanother specific embodiment, a display assembly 102 can include anactive-matrix organic light-emitting diode utilized in a smartphone ortablet computer. Some other examples of a display assembly 102 caninclude an electroluminescent display (ELD) or a plasma display panel.

In the embodiment illustrated in FIG. 2, the fingerprint sensor 100 caninclude a display assembly 102 (e.g., a liquid crystal display) with asensor glass layer 108 disposed on the display assembly 102. In thisembodiment, a receive layer 112 and a transmit layer 104 can bepatterned into a first layer 122 (e.g., a single indium tin oxide layerincluding the receive layer 112 and the transmit layer 104) on thesensor glass layer 108 with conductive bridge(s) 118 formed in a secondlayer 124 of indium tin oxide (or other suitable material). The firstlayer 122 can be physically and/or electrically separated from thesecond layer 124 by at least one dielectric patch 120 (e.g., a thin-filmpatch) at each row/column intersection, which can make the columns ofthe receive layer 112 continuous.

The fingerprint sensor 100 can sense touch, styli, hover, and gestures.This is done by electrically ganging the transmit layer 104 (e.g.,transmit rows) and also ganging the receive layer 112 (e.g., receivecolumns) to form wider sensing elements. In some implementations, suchas those shown in FIGS. 3-4, the fingerprint sensing portion 103 can belimited to a small area of the fingerprint sensor 100 and protectivecover layer 116. In these implementations, an example 1 cm² fingerprintsense area may provide adequate fingerprint sensing with a pitch of 50microns, which can require about 200 transmit lines and about 200receive lines. Each of these lines can be electrically and/or physicallyconnected to a contact pad on a controller 130.

In some implementations, the fingerprint sensing portion 103 of anoverall device (e.g., smartphone, tablet computer, etc.) can include alarger portion of the entire cover glass device, such as the touch-paneldevice shown in FIG. 5. A larger area fingerprint sensor 100 may enableexpanded functionality.

As shown in FIG. 6, the fingerprint sensor 100 can include a controller130 configured to authenticate a user. The controller 130 may furtherinclude a processor 132, a communications module 136, and/or memory 134.In implementations, the processor 132 can provide processingfunctionality for the controller 130 and may include any number ofprocessors, micro-controllers, or other processing systems and residentor external memory for storing data and other information accessed orgenerated by the controller 130. The processor may execute one or moresoftware programs, such as a fingerprint sensing application, whichimplement techniques described herein. The processor 132 is not limitedby the materials from which it is formed or the processing mechanismsemployed therein, and as such, may be implemented via semiconductor(s)and/or transistors (e.g., using electronic integrated circuit (IC)components), and so forth.

The communications module 136 can be operatively configured tocommunicate with components of the fingerprint sensor 100 and/or systemhost. The communications module 136 can also be communicatively coupledwith the processor 132 (e.g., for communicating inputs from thefingerprint sensor 100 to the processor 132). The communications module136 and/or the processor 132 can also be configured to communicate witha variety of different networks, including the Internet, a cellulartelephone network, a local area network (LAN), a wide area network(WAN), a wireless network, a public telephone network, and/or anintranet, for example. In one implementation, the communications module136 can include sensing lines between components of the fingerprintsensor 100.

The memory 134 is an example of tangible computer-readable media thatprovides storage functionality to store various data associated withoperation of the controller 130, such as software programs and/or codesegments, algorithms, or other data to instruct the processor 132 and/orother components of the controller 130 to perform the steps and/orfunctions described herein. Thus, the memory 134 can store data, such asa program of instructions for operating a fingerprint sensor 100(including its components), data, and so on. Although a single memory134 is described, a wide variety of types and combinations of memory(e.g., tangible memory, non-transitory) may be employed. The memory 134may be integral with the processor 132, may comprise stand-alone memory,or may be a combination of both.

The memory 134 may include removable and non-removable memorycomponents, such as Random Access Memory (RAM), Read-Only Memory (ROM),Flash memory (e.g., a Secure Digital (SD) memory card, a mini-SD memorycard, and/or a micro-SD memory card), magnetic memory, optical memory, aUniversal Serial Bus (USB) memory device, hard disk memory, externalmemory, and other types of computer-readable storage media. Inimplementations, the fingerprint sensor 100 and/or memory 134 mayinclude removable Integrated Circuit Card (ICC) memory, such as memoryprovided by a Subscriber Identity Module (SIM) card, a UniversalSubscriber Identity Module (USIM) card, a Universal Integrated CircuitCard (UICC), and so on.

CONCLUSION

Although the subject matter has been described in language specific tostructural features and/or process operations, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. A fingerprint sensor assembly, comprising: acontroller; a metal layer configured to be electrically coupled to thecontroller; a transmit layer electrically connected to the metal layerand the controller; a sensor glass layer including at least onethrough-glass via, where the transmit layer is disposed on a first sideof the sensor glass layer, and where the transmit layer is electricallycoupled to the at least one through-glass via; a receive layer disposedon a second side of the sensor glass layer, where the receive layer iselectrically coupled to the at least one through-glass via; and aprotective cover layer disposed on the receive layer.
 2. The fingerprintsensor assembly of claim 1, wherein the protective cover layer includesaluminum oxide.
 3. The fingerprint sensor assembly of claim 2, whereinthe aluminum oxide is about 1 μm in thickness.
 4. The fingerprint sensorassembly of claim 1, wherein the protective cover layer includes asingle-crystal sapphire layer.
 5. The fingerprint sensor assembly ofclaim 4, wherein the single-crystal sapphire layer is between about 100μm and 200 μm in thickness.
 6. The fingerprint sensor assembly of claim1, wherein the protective cover layer includes silicon carbide.
 7. Thefingerprint sensor assembly of claim 1, wherein the protective coverlayer includes diamond.
 8. The fingerprint sensor assembly of claim 1,wherein at least one of the receive layer or the transmit layer includesindium tin oxide.
 9. The fingerprint sensor assembly of claim 1, whereinthe at least one through-glass via includes a metal-filled blind viathat extends from the first side of the sensor glass layer to the secondside of the sensor glass layer, where the metal-filled blind via isconfigured to provide capacitive coupling between the transmit layer andthe receive layer.
 10. A cover glass assembly with a high-resolutionelectric field sensor, comprising: a transmit layer electricallyconnected by a metal layer to a controller; a sensor glass layerincluding at least one through-glass via, where the transmit layer isdisposed on a first side of the sensor glass layer and is electricallycoupled to the at least one through-glass via; a receive layer disposedon a second side of the sensor glass layer, where the receive layer iselectrically coupled to the at least one through-glass via; and aprotective cover layer disposed on the receive layer, where the coverglass device is configured to include a touch-panel device.
 11. Thecover glass assembly of claim 10, where the controller is configured toimage fingerprints.
 12. The cover glass assembly of claim 10, where thecontroller is configured to image a user's touch.
 13. The cover glassassembly of claim 10, where the protective cover layer includes aluminumoxide.
 14. The cover glass assembly of claim 13, wherein the aluminumoxide is about 1 μm in thickness.
 15. The cover glass assembly of claim10, where the protective cover layer includes a single-crystal sapphirelayer.
 16. The cover glass assembly of claim 15, wherein thesingle-crystal sapphire layer is between about 100 μm and 200 μm inthickness.
 17. The cover glass assembly of claim 10, where theprotective cover layer includes silicon carbide.
 18. The cover glassassembly of claim 10, where the protective cover layer includes diamond.19. A fingerprint-sensing mobile device, comprising: a display assemblyconfigured for a mobile device; a transmit layer electrically connectedby a metal layer to a controller, where the controller is electricallycoupled to the display assembly; a sensor glass layer including at leastone through-glass via, where the transmit layer is disposed on a firstside of the sensor glass layer and is electrically coupled to the atleast one through-glass via; a receive layer disposed on a second sideof the sensor glass layer, where the receive layer is electricallycoupled to the at least one through-glass via; and a protective coverlayer disposed on the receive layer.
 20. The fingerprint-sensing mobiledevice of claim 19, where the display assembly includes a liquid crystaldisplay.